2022 年 39 巻 3 号 p. 346-349
Kelch–like protein 11 (KLHL11)–associated paraneoplastic syndrome (PNS) has been newly categorized as PNS. The corresponding syndromes are cerebellar and/or brainstem involvement, and in the fewer cases, limbic encephalitis. Hearing loss or tinnitus often precedes other symptoms. Findings of cerebrospinal fluid show inflammatory (protein 50mg/dL or greater and leukocyte counts exceeding 5 cells/µL) with oligoclonal bands in over 80% cases. The most common associated tumor is testicular germ cell tumor, especially seminoma. The primary testicular tumor is often spontaneously regressed with or without metastasis in lymph nodes, called a burned–out testicular tumor. Ultrasonography of testis is useful for such cases because it can detect the suggestive findings of burned–out tumors such as fibrosis and microlithiasis as hypoechoic area. The principles for management are treatment of underlying cancer and immunotherapy. KLHL11–PNS may have a more refractory course than PNS associated with antibodies against neural cell surface antigens since KLHL11 antibodies are targeting intracellular autoantigens and cause cytotoxic T–cell–mediated pathogenesis. A recent paper published by Autoimmune Encephalitis Alliance Clinicians Network recommends that tumor treatment and intravenous methylprednisolone followed by short oral taper should be performed as first–line therapy. If there is no improvement cyclophosphamide can be the next option. Then experimental therapy like IL–6 inhibitor or bortezomib can be considered in non–responded cases.
